Power decrease based on packet type

ABSTRACT

Techniques for controlling one or more audio amplifiers in or associated with a device coupled on a local area network are disclosed. An example playback device includes a processor, an amplifier, a network interface, and a memory. The memory includes a software module that, when executed by the processor, causes the playback device to: operate in a first power mode in which the amplifier consumes a first amount of power; while operating in the first power mode, determine that a defined time has passed since receiving, via the network interface, a specified type of data packet; and based on determining that the defined time has passed since receiving the specified type of data packet, transition from operating in the first power mode to operate in a second power mode in which the amplifier consumes a second amount of power, wherein the first amount of power is greater than the second amount of power.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority as a continuation of U.S. patentapplication Ser. No. 13/212,889, filed on Aug. 18, 2011, for “Method andSystem for Controlling Amplifiers”, and to U.S. patent application Ser.No. 10/845,805, filed on May 15, 2004, for “Method and System forControlling Amplifiers,” both of which are hereby incorporated byreference in their entirety for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is generally related to the area of audio technologies. Inparticular, the invention is related to controlling of audio amplifiersin devices based upon data traffic detection.

2. The Background of Related Art

Automatic power shutdown is an important feature in many electricalappliances. One of the appliances commonly seen is a stereo system thatincludes a powered subwoofer. The subwoofer is automatically shutdownwhen the stereo system is powered off or produces no sound (e.g., in CDmode with no CD is played). On the other end, the subwoofer isautomatically tuned on when the stereo system is powered on, thuseliminating the need of turning on or off two devices manually orsequentially. Another example is an uninterruptible power supply (UPS)supporting a computer system. The UPS provides power in an event thatregular power to the computer system is suddenly off. As an automatedpreventative measure, the computer system is configured to shut downitself when the UPS is running on a low battery level or beyond apredetermined time so as to avoid corrupting files, or damaging otherparts in the computer system.

The implementation of the automatic power shutdown feature is largelybased upon special circuitry or analog control circuits to detect asignal level against a predetermined level. In the stereo systemexample, if audio signals to the subwoofer are not detected orsubstantially lower than a fixed level for a period of time, thesubwoofer is sent a signal to be powered off. Likewise, when audiosignals to the subwoofer are detected, the subwoofer is sent a signal tobe powered on. In the UPS example, the detection mechanism is similar.The battery in the UPS is constantly or periodically measured against apredetermined level or the operation time thereof is measured. Wheneither one of the measurements is below a certain level, the computersystem receives a signal or an instruction that triggers the automaticshutdown process.

The analog solution of automatic power shutdown is not effective whenused in a distributed system comprising multiple devices that need toautomatically shut down while not in use. For example, a plurality ofnetworked audio devices each of which has or associated with one or morepower amplifiers share audio sources. The detection of an analog signalto one of the audio devices on a data network would be difficult andineffective. Additional hardware (i.e., circuitry), if needed, wouldincrease the cost and complexity of such system. There is, therefore, aneed for solutions of automatic shutdown suitable for such systemwithout adding extra hardware.

SUMMARY OF THE INVENTION

This section is for the purpose of summarizing some aspects of thepresent invention and to briefly introduce some preferred embodiments.Simplifications or omissions in this section as well as in the abstractor the title of this description may be made to avoid obscuring thepurpose of this section, the abstract and the title. Suchsimplifications or omissions are not intended to limit the scope of thepresent invention.

In general, the present invention pertains to controlling one or moreaudio amplifiers in or associated with a device coupled on a local areanetwork and receiving at least one selected source from other devicesalso coupled on the network. The device may be an audio device forplaying back audio resources stored on the other devices. According toone aspect of the present invention, an automatic shutdown controlmodule is provided in the device to power down the audio amplifiers whenthere is no audio data flow coming to the device or power up the audioamplifiers when there is audio data flow coming to the device.

All types of traffic may be present on a local area network, includingdata other than those from an audio source. The present invention reliesupon traffic of only the data from one or more audio sources to controlthe operation of audio amplifiers. When audio traffic to a device isabsent for a defined time, an audio amplifier in or associated with thedevice is automatically powered down. The defined time may be a fixedtime or derived from a set of data collected over a time periodregarding a time lapse not intended for powering down the audioamplifier.

According to another aspect of the present invention, the procedure topower down or power up the amplifiers is in accordance with ahysteresis, wherein the hysteresis, being lagging of an effect behindits cause, protects the amplifiers and makes the powering-down orpowering-up procedure unnoticeable to a user. As such, theimplementation of the hysteresis protects the amplifiers from beingturned on or off in quick succession.

The present invention may be implemented in many forms includingsoftware, hardware or a combination of both. According to oneembodiment, the present invention is an apparatus for controlling anaudio amplifier, the apparatus comprises: a network interfacecommunicating with a data network, a control module, coupled to thenetwork interface, configured to detect any data packets coming from thedata network; when none of the data packets is detected relating to anaudio source for a defined time, the control module causing the audioamplifier to be powered down; when the data packets is detected relatingto an audio source, the control module causing the audio amplifier to bepowered on.

According to another embodiment, the present invention is a method forcontrolling an audio amplifier, the method comprises detecting any datapackets coming from a network; when none of the data packets is detectedrelating to an audio source for a defined time, causing the audioamplifier to be powered down; when the data packets is detected relatingto an audio source, causing the audio amplifier to be powered on.

One of the objects, features, advantages of the present invention is touse data traffic pertaining only to the data of the audio source tocontrol audio amplifiers.

Other objects, features, and advantages of the present invention willbecome apparent upon examining the following detailed description of anembodiment thereof, taken in conjunction with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIG. 1 shows a configuration in which the present invention may bepracticed, the configuration may represent, but not be limited to, apart of a residential home, a business building or a complex;

FIG. 2A shows an exemplary functional block diagram of a zone player inaccordance with the present invention;

FIG. 2B shows an exemplary panel configuration of a zone playeraccording to one embodiment of the present invention;

FIG. 2C shows a remote controller that may be used to control one of thezone players in a distributed audio system;

FIG. 3A shows a flowchart or process of powering on an amplifieraccording to one embodiment of the present invention;

FIG. 3B shows a flowchart or process of powering down an amplifieraccording to one embodiment of the present invention;

FIG. 4 shows an exemplary implementation of controlling an audioamplifier.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention pertains to designs of controlling one or moreaudio amplifiers in or associated with a device coupled on a local areanetwork and receiving at least one selected source from other devicesalso coupled on the network. The device may be an audio device forplaying back audio resources stored on the other devices. According toone aspect of the present invention, an automatic shutdown controlmodule is provided in the device to power down the audio amplifiers whenthere is no audio data flow coming to the device or power up the audioamplifiers when there is audio data flow coming to the device. In oneembodiment, the procedure to power down or power up the amplifiers is inaccordance with a hysteresis, wherein the hysteresis, being lagging ofan effect behind its cause, protects the amplifiers and makes thepowering-down or powering-up procedure unnoticeable to a user.

The detailed description of the present invention is presented largelyin terms of procedures, steps, logic blocks, processing, or othersymbolic representations that directly or indirectly resemble theoperations of devices or systems that can be used in networks. Thesedescriptions and representations are typically used by those skilled inthe art to most effectively convey the substance of their work to othersskilled in the art.

Reference herein to “one embodiment” or “an embodiment” means that aparticular feature, structure, or characteristic described in connectionwith the embodiment can be included in at least one embodiment of theinvention. The appearances of the phrase “in one embodiment” in variousplaces in the specification are not necessarily all referring to thesame embodiment, nor are separate or alternative embodiments mutuallyexclusive of other embodiments. Further, the order of blocks in processflowcharts or diagrams representing one or more embodiments of theinvention do not inherently indicate any particular order nor imply anylimitations in the invention.

Referring now to the drawings, in which like numerals refer to likeparts throughout the several views. FIG. 1 shows an exemplaryconfiguration 100 in which the present invention may be practiced. Theconfiguration may represent, but not be limited to, a part of aresidential home, a business building or a complex. There are a numberof audio devices of which three exemplas 102, 104 and 106 are shown.Each of the audio devices may be installed or provided in one particulararea or zone and hence referred to as a zone player herein.

As used herein, unless explicitly stated otherwise, an audio source oraudio sources are in digital format and can be transported over a datanetwork. A term “power down” or “power off” an audio amplifier does notnecessarily mean that a power supply to the audio amplifier iscompletely disconnected and in most cases mean that the audio amplifieroperates in a sleeping mode so as to consume a minimum amount of power.

To facilitate the understanding of the present invention, it is assumedthat the configuration 100 represents a home. Thus, the zone player 102and 104 may be in two bedrooms respectively while the zone player 106may be in a living room. All of the zone players 102, 104 and 106 arecoupled to a data network 108. In addition, a computing device 110 isshown to be coupled on the network 108. In reality, any other devicessuch as a home gateway device, a storage device, or an MP3 player may becoupled to the network 108 as well.

The network 108 may be a wired network, a wireless network or acombination of both. In one example, all devices including the zoneplayers 102, 104 and 106 are coupled to the network 108 by wirelessmeans based on an industry standard such as 802.11 or WiFi. In anotherexample, all devices including the zone players 102, 104 and 106 arepart of a local area network that communicate with a wide area network(e.g., the Internet).

Many devices on the network 108 are configured to download and storeaudio sources. For example, the computing device 110 can download audiosources from the Internet and store the downloaded sources locally forsharing with other devices on the Internet or the network 108. Thecomputing device 110 can also be configured to receive streaming audios.Shown as a stereo system, the device 112 is configured to convert ananalog source (e.g., from broadcasting) to a digital audio source orretrieve an audio source (e.g., from a compact disk). In accordance withthe present invention, the audio source may be shared among the deviceson the network 108. Although each of the zone players may be configuredto be able to download or store audio resources, the followingdescription is based on the assumption that the zone players are pureplayers and need to retrieve selected audio sources from other devices(e.g., the compute system 110) for playback.

FIG. 2A shows an exemplary functional block diagram of a zone player 200in accordance with the present invention. The zone player 200 includes anetwork interface 202, a processor 204, a memory 206, an audioprocessing circuit 208, an automatic shutdown control module 210, and anaudio amplifier 212. The audio amplifier 212 may represent multipleamplifiers. The network interface 202 facilitates a data flow between adata network (i.e., the data network 108 of FIG. 1) and the zone player200 and typically executes a special set of rules (i.e., a protocol) tosend data back and forth. One of the common protocols is TCP/IP(Transmission Control Protocol/Internet Protocol) commonly used in theInternet. In general, a network interface manages the assembling of anaudio source or file into smaller packets that are transmitted over thedata network or reassembles received packets into the original source orfile. In addition, the network interface 202 handles the address part ofeach packet so that it gets to the right destination or interceptspackets destined for the zone player 200.

FIG. 2B shows an exemplary panel configuration 220 of the zone player200 according to one embodiment of the present invention. It can beappreciated by those skilled in the art that, the zone player 200 isconfigured to be able to communicate with other devices via the dataports 222 and share the audio sources with other zone players. Inparticular, the data ports 222 allow the zone player 200 to retrieve aselected song or a selected piece of music from a device on the network108.

The processor 204 is configured to control the operation of other partsin the zone player 200. The memory 206 may be loaded with softwaremodules that can be executed by the processor 204 to achieve desiredtasks. According to one aspect of the present invention, a softwaremodule implementing one embodiment of the present invention is executed,the automatic shutdown control module operates in accordance with thesoftware module to control the operation of the audio amplifier 212 soas to turn the audio amplifier 212 off when the zone player 200 is notin use or turn the audio amplifier 212 on when the zone player 200 is toplay back a selected audio source.

The audio processing circuit 208 resembles most of the circuitry in anaudio playback device and includes one or more digital-to-analogconverters (DAC), an audio preprocessing part, an audio enhancement partor a digital signal processor and others. In operation, when an audiosource is retrieved via the network interface 202, the audio source isprocessed in the audio processing circuit 208 to produce analog audiosignals. The processed analog audio signals are then provided to theaudio amplifier 212 for playback on nearby speakers.

The audio amplifier 212 is typically an analog circuit that powers theprovided analog audio signals to drive one or more speakers. The audioamplifier 212, which may be a separate unit outside of the zone player200, is a primary source to draw most of the power to drive the system.Prolonged operation of the audio amplifier 212 without actuallyamplifying anything, namely when no analog audio signals are provided,is not desirable. Leaving the audio amplifier 212 on, even if it is notactually in use, consumes the power, shortens the operating lifethereof, and may generate excessive heat that can cause damage to nearbyparts. In other words, it is desired at all times that the audioamplifier 212 is powered down when the zone player 200 is not receivingany audio sources for playback.

The RF interface 214 provides wireless means for the zone player 200 tocommunicate with a controller, preferably a portable. An example of thecontroller 240 is shown in FIG. 2C. According to one embodiment, thewireless means is based on an industry standard (e.g., infrared, radio,wireless standard 802.11b or 802.11g). The controller 240 may be used tofacilitate a selection of a plurality of audio sources available on thenetwork, controlling operation of the zone player 200 through the RFinterface 214. When a particular audio source is being played in thezone player 200, a picture, if there is any, associated with the audiosource may be transmitted from the zone player 200 to the controller240. As shown in FIG. 2C, many operations of the zone player 200 can beremotely controlled via the RF interface 214.

FIG. 3A and FIG. 3B show respectively a flowchart or process 300 and 330of a module implementing one embodiment of the present invention. Theprocess 300 and 330, which is preferably understood in conjunction withthe previous figures, may be implemented in software, hardware, or acombination of both. According to one embodiment, the module is embeddedin a zone player (e.g., in the memory 206 in FIG. 2A) and can beexecuted to control the automatic shutdown of the audio amplifier in thezone player or associated with the zone player.

The process 300 of FIG. 3A implements an automatic turn-on (i.e., powerup) capability. At 302, the process 300 detects if there is any audiosource received. Depending on implementation, such detection may beimplemented in a few places including the network or within the zoneplayer. According to one embodiment, the module is configured to detectwhether there is any data packets (e.g., part of the audio stream) inthe network interface or other layers thereof. When no data flow isdetected, the process 300 stays where it is at 302, namely, no actionwould be taken. When a data flow is detected, the process 300 moves onto304.

It should be noted that the criteria of detecting the presence of datamay vary depending on an exact implementation of the distributed digitalaudio system. In one embodiment, the zone player may be configured toreceive data other than the audio data, where the audio data representsthe audio source and the data other than the audio data may includecommands or control information. Accordingly, a data packet may beanalyzed to determine whether it represents part of an audio source. Ifthe data packet is other than the audio data, the process 300 stayswhere it is at 302. The process 300 moves onto 304 only when one or moreaudio data packets are detected.

At 304, the status of the amplifier is determined. The amplifier may bealready powered on and is operating, in which case the process 300 doesnothing by going to 312. This happens usually in the middle of playingback a piece of music or in an interim (i.e., a temporary lapse) thathappens, for example, when a new audio source is selected or to bestarted after a current one is just finished or jumping ahead of a fewtracks in an audio source. In another case, however, the amplifier hasbeen powered off and now needs to be turned back on to facilitate theplayback of a received audio source. The process 300 now goes to 306 topower up the amplifier.

To avoid a sudden noise coming out from speakers when the amplifier istuned on or off, the control of the amplifier is performed in accordancewith a hysteresis, wherein the hysteresis, being lagging of an effectbehind its cause, protects the amplifiers and makes the powering-down orpowering-up procedure unnoticeable to a user. In other words, thehysteresis mutes or smoothes out possible noises or frequency as aresult of the amplifier being “ON” from “OFF” or being “OFF” from “ON”.

In one embodiment, the amplifier is always put into mute mode first whenpowered off. The mute mode can be realized in several ways that areknown to those skilled in the art. For example, a connection from theamplifier to the speakers can be electronically disconnected. Hence, apreferable sequence of turning on an amplifier is to power on theamplifier first and then unmute or activate the amplifier. Accordingly,after the amplifier is powered on at 306, the process 300 moves to 308to activate the amplifier.

In one embodiment, to control the operation of the amplifier precisely,one or more parameters about the status of the amplifier are used. Theparameters may be referred to when the status of the amplifier isdetermined. At 310, the status of the amplifier is set to be “ON”. Theprocess 300 then goes to 312 where the amplifier operates in workingmode, namely amplifying processed analog audio signals to drivespeakers.

On the other end, the process 330 of FIG. 3B implements an automaticturn-off (i.e., power down). At 332, the process 330 detects if there isany audio source received. As described before, depending onimplementation, such detection may be implemented in a few placesincluding the network or within the zone player. According to oneembodiment, the module is configured to detect whether there is any datapackets (e.g., part of the audio stream) in the network interface orother layers thereof. When a data flow is detected, the process 330stays where it is at 332, namely, no action would be taken. When no dataflow is detected, the process 330 moves onto 333. There are certainsituations in which no (audio) data flow can be detected, for example,during two separate songs. To ensure a proper shut-down process, at 333,a time lapsed for no data flow is measured. In one embodiment, the timeis compared to a predetermined time, for example, 3 seconds, if the timeis shorter than the predetermined time, namely before the predeterminedtime is lapsed, the process 330 goes back to 332 to continue thedetection of the data flow. When the time is longer than thepredetermined time, the process 330 moves onto 334.

According to one embodiment, to avoid powering the amplifier down duringan interim (e.g., switching from one music to another, browsing acollection of songs), the time to determine whether the amplifier shallbe powered down is implemented intelligently. For example, using thepredetermined time as a base or a reference point, historical data onthe durations between two consecutive pieces of music beyond thepredetermined time is collected. Accordingly, an appropriate time canthus be derived from the data. As the process 300 as well as 330 can beimplemented in software, various algorithms to determine suchappropriate time are known to those skilled in the art and can beadopted relatively easy in the software implementation. It may beappreciated by now that the current invention provides the flexibilityto determine how to control the amplifier, while the prior art shutdownsystems obviously lack such control flexibility and must be equippedwith additional circuitry.

It should be noted that the data flow herein pertain to an audio source.In one embodiment, the zone player may be configured to receive dataother than the audio data, where the audio data represents the audiosource and the data other than the audio data may include commands orcontrol information). Accordingly, a data packet may be analyzed todetermine whether it represents part of an audio source that is selectedfor playback. If the data packet is indeed the audio data, the process330 stays where it is at 332. The process 330 moves onto 334 only whenno audio data is detected.

At 334, the status of the amplifier is checked. If the status of theamplifier shows that it is already off, there is no further actionneeded. If the status of the amplifier shows that the amplifier has been“ON”, the process 330 goes to 336 to first mute the amplifier and thenpower down the amplifier at 338. After the amplifier is powered down orthe status of the amplifier has changed, the process 330 goes to 340 toupdate the status of the amplifier by resetting one or more parametersrepresenting the status thereof to “OFF” at 340. Consequently, theamplifier goes to rest mode at 342.

Referring now to FIG. 4, there shows an exemplary implementation 400 ofcontrolling an audio amplifier 402. The automatic shutdown controlmodule 412 operates in response to the detection of the audio datapackets. At least two electronic connections 406 and 408 are controlledby the automatic shutdown control module 412. It is understood by thoseskilled in the art that the electronic connections 406 and 408 are notnecessarily switches. Functionally, signals from the audio amplifier tospeakers 410, power from a power supply 404 to the audio amplifier 402or vice versa are controlled by the automatic shutdown control module412.

In one embodiment, there is a small amount of power supplied to theaudio amplifier 402 via an uncontrolled electronic connection 414 tokeep a portion of the audio amplifier 402 to operate or to react to aninstruction for the status of the audio amplifier to change. Inoperation, when the audio amplifier 402 is powered down, the audioamplifier 402 is to be deactivated or muted first and then powered down.This may be achieved by disconnecting the electronic connection 406 orpreventing any signal from going to the speakers 410, and followed bydisconnecting the electronic connection 408. Likewise, when the audioamplifier 402 is powered up to operate in working mode, the audioamplifier 402 is powered up and then activated. This may be achieved byrestoring the electronic connection 408 and followed by restoring theelectronic connection 406.

The present invention can be implemented in many ways, each of which mayyield one or more of the following benefits, advantages or features.First, the control of an audio amplifier is based on a data flow of anaudio source. The audio source is retrieved and comes from a networkthat has other data traffics. The present invention uses data trafficpertaining only to the data of the audio source to control the audioamplifier. Second, a flexible mechanism in terms of time of the absenceof an audio data flow is provided, which could be hardly realized in aprior art system involving hardware. Third, the software-basedimplementation of controlling one or more amplifiers makes it possibleto determine an appropriate define time, with a more sophisticatedalgorithm, to power down or up the amplifiers. In reality, it isdesirable to control the amplifiers intelligently so as to achieve alonger operating lifespan of the amplifiers and save more power. Otherbenefits, advantages or features can be appreciated by those skilled inthe art given the detailed description herein.

While the present invention has been described with reference tospecific embodiments, the description is illustrative of the inventionand is not to be construed as limiting the invention. Variousmodifications to the present invention can be made to the preferredembodiments by those skilled in the art without departing from the truespirit and scope of the invention as defined by the appended claim. Forexample, the present invention may also be applied to other forms ofamplifiers that operate on signals from digital sources. One applicationis pertains to digital video, in which a visual amplifier (e.g., adisplay) consumes most of the power. Evidently, the present inventioncan be readily applied to prolong the operating lifespan of theamplifier as well as save substantially the power. Accordingly, thescope of the present invention is defined by the appended claims ratherthan the forgoing description of embodiments.

The invention claimed is:
 1. A playback device comprising: one or moreprocessors; an amplifier; a network interface; and tangible,non-transitory, computer-readable memory comprising instructions that,when executed by the one or more processors, cause the playback deviceto: operate in a first power mode in which the amplifier consumes afirst amount of power; while operating in the first power mode, receiveone or more packets addressed to the playback device, and determine thata defined time has passed since receiving a specified type of datapacket; and after determining that the defined time has passed sincereceiving the specified type of data packet, transition from operatingin the first power mode to operate in a second power mode in which theamplifier consumes a second amount of power, wherein the first amount ofpower is greater than the second amount of power.
 2. The playback deviceof claim 1, wherein the specified type of data packet is a data packetreceived from an audio source.
 3. The playback device of claim 1,wherein the specified type of data packet is a data packet relating toan audio source.
 4. The playback device of claim 1, wherein theamplifier comprises an analog circuit.
 5. The playback device of claim1, wherein the specified type of data packet comprises a data packetcomprising audio content received from an audio source.
 6. The playbackdevice of claim 1, wherein the specified type of data packet comprises apacket of an audio stream received from an audio source.
 7. The playbackdevice of claim 1, wherein the specified type of data packet comprises acontrol packet that comprises control information relating to an audiostream.
 8. The playback device of claim 1, wherein causing the amplifierto operate in the second power mode comprises switching at least oneelectronic connection.
 9. The playback device of claim 1, wherein thesecond amount of power is no power.
 10. The playback device of claim 1,wherein the second amount of power is greater than no power.
 11. Theplayback device of claim 1, wherein the instructions, when executed bythe one or more processors, further cause the playback device to: whileoperating in the first power mode, play back an audio stream in responseto receiving a data packet comprising a command to start playback of theaudio stream.
 12. The playback device of claim 11, wherein the specifiedtype of data packet comprises a control packet comprising a command tostop playback of the audio stream.
 13. A method comprising: a playbackdevice operating in a first power mode in which an amplifier of theplayback device consumes a first amount of power; while operating in thefirst power mode, the playback device receiving one or more packetsaddressed to the playback device, and determining that a defined timehas passed since receiving a specified type of data packet; and afterdetermining that the defined time has passed since receiving thespecified type of data packet, the playback device transitioning fromoperating in the first power mode to operating in a second power mode inwhich the amplifier consumes a second amount of power, wherein the firstamount of power is greater than the second amount of power.
 14. Themethod of claim 13, wherein the specified type of data packet is a datapacket associated with an audio source.
 15. The method of claim 13,wherein the specified type of data packet comprises a data packetreceived from an audio source.
 16. The method of claim 13, wherein thespecified type of data packet comprises a packet of an audio streamreceived from an audio source.
 17. The method of claim 13, wherein thespecified type of data packet comprises a control packet comprisingcontrol information relating to an audio stream received from an audiosource, wherein the control packet is received from one of the audiosource or a controller that is separate from the audio source.
 18. Themethod of claim 13, wherein the second amount of power is greater thanno power.
 19. A tangible, non-transitory computer-readable storagemedium having stored therein instructions executable by one or moreprocessors, wherein the instructions, when executed by the one or moreprocessors, cause a playback device to perform a method comprising:operating the playback device in a first power mode in which anamplifier of the playback device consumes a first amount of power; whileoperating in the first power mode, the playback device receiving one ormore packets addressed to the playback device, and determining that adefined time has passed since receiving a specified type of data packet;and after determining that the defined time has passed since receivingthe specified type of data packet, transitioning the playback devicefrom operating in the first power mode to operating in a second powermode in which the amplifier consumes a second amount of power, whereinthe first amount of power is greater than the second amount of power.20. The tangible, non-transitory computer-readable storage medium ofclaim 19, wherein the specified type of data packet comprises one of adata packet comprising audio content or a control packet comprisinginstructions to start playback of audio content.